Wednesday, December 28, 2011

My Earthquake

I was happy to see Ron's call for posts Accretionary Wedge #41, and I knew right away what my post would be about, but I've had to wait until my thesis was submitted (done) before I could write it up.

When I was an exchange student in New Zealand in 1994-1995 I kept a diary every day. A lot of it is teenage rubbish, but some of it records an amazing year of experiences. Here is an excerpt from March 23, 1995:

There was an earthquake this morning. It lasted 20 seconds, most of which I spent shaking (because I was terrified) in a doorway. About halfway through, it got worse. Apparently it was centered about 75km down beneath the Marlborough Sounds and measured 5.9 on the Richter Scale. It was felt as far away as Auckland and Dunedin though!
It's scary, an earthquake. I hate them. I remained pretty calm today, though afterwards I shoved a whole piece of toast in my mouth at once. That's how bad my nerves were. After school when I was in the kitchen where I was when it hit, I felt scared again. I'll never forget this morning. I think I heard it coming before it hit, but I'm not sure. I do remember standing at the bench [Kiwi-speak for kitchen counter], looking all around me, and wondering when I should move into a doorway.
I hope and pray  that the predicted 'big one' never hits New Zealand, especially while I'm here!

Hanging on the wall of my apartment, beside my undergraduate degree, is a fading printout of the earthquake report. Not that I need a reminder -- I've never forgotten that morning. From what I can recall, there was no significant damage from that quake--things fell off the shelves in some shops, but that was about it.  My friends who were already in cars or buses on the way to school didn't feel it. I don't remember being as terrified as my diary said I was. I do remember hearing it, and thinking it was an awfully big truck driving up the street to make that rumbling noise. I remember the toast too.

I did a search on GeoNet to try to find "my earthquake" and there it was, listed as the Cape Jackson earthquake (ID 136357).  The magnitude and depth in the records have both been upgraded since the original report: it was magnitude 6.449 at a depth of 87.08km.

1995 was a big year for earthquakes in New Zealand--not for big quakes, necessarily, but lots of little ones which I'm guessing were related to the eruption of Mount Ruapehu in October of that year (after I was already back in Canada).

Friday, December 16, 2011

Geology photo of the day - Friday

For the final day of geology-photo-of-the-day week (this has been a fun week Evelyn, and I may start posting photos more regularly too!) I'll leave you with this photo from White Island, in New Zealand. My first exposure to this island was in December 1994, when I spent Christmas holidays with my host family at their bach in the Bay of Plenty. Back then, it was just a fascinating, steaming island on the horizon.

In September of this year, I spent a few days with the same host family at the home they built in the Bay of Plenty, and I decided to treat myself to a day trip out to White Island. It was well worth it--besides beautiful weather and orcas on the way to the island, it was really cool to be on/in a volcano!

Thursday, December 15, 2011

Geology photo of the day - Thursday

Today's photo of the day (see the beginning of the meme) is from the Bolivian Altiplano. This is the Puchuni Valley, near Estancia Palluma. We were there to map some Cenozoic beds, but I believe these ones are Jurassic (or older).

Wednesday, December 14, 2011

Wednesday Picture of the Day

Since this whole meme was sponsored by Evelyn Mervine, and she posted a photo of coral today, I was inspired to post a photo of modern carbonates. This one is from the Great Barrier Reef. If I was a carbonate sedimentologist, I would probably spend more time than necessary studying modern analogs.

Tuesday, December 13, 2011

Tuesday Geology Photo

As part of the geology-photo-a-day week, here's my photo for today. This was taken en route to doing some field work in late August 2010. It is of the Cardium Formation (one of Alberta's most prolific reservoir formations) at the spectacular Ram Falls in the foothills of west-central Alberta.

Monday, December 12, 2011

Monday Geology Photos

Evelyn at Georneys invited us to join her this week in posting a geology photo a day. It's a busy week for me, trying to finish the final chapter of my thesis before I settle in for some thorough editing. I can't promise that I'll get around to finishing the blog posts I have in the works, but a photo-a-day seems manageable, especially since sifting through them to find especially cool ones makes for a nice break.

Today's photo is from my visit to Australia in September. It's from the top of a red sand dune, between Lake Amadeus and Mount Connor, in the Northern Territory. I forgot to take a close-up photo of the sand, but it was hot and fine-grained and felt silky smooth on my bare feet.

The pinkish haze on the horizon is the smoke from the bush fires that were a dominant character during my time in the Northern Territory.

It's kind of cheating on the photo-a-day theme, but here's another photo, showing a different dune in the background, giving a sense of how big these things actually are.  In fact, many of the viewing areas at Uluru and Kata Tjuta are on top of dunes.

If you fly to Alice Springs from Sydney, as I did, you fly over the Simpson Desert, which is a "sea" of dunes.

Thursday, November 24, 2011

All Geology Is Connected

Yesterday, after attending a talk that got me thinking, I tweeted this: 
At a talk about how/where diamonds form I heard about "diamonds" that plug gas wells #AllGeologyIsConnected
The talk was part of the colloquium series in the department where I'm a grad student. A couple of the faculty work very hard to bring in guest speakers every two weeks to give talks about various aspects of geoscience. The room is never full for these talks. I know not everyone can make it to every talk, but I also suspect some people don't come to these the talks if they are not "relevant" to their own research. They're missing out.

I have geologic interests outside of my own research. I want to learn about other aspects of geology. Besides which, I find going to "unrelated" geology talks sparks my thought process, and I sometimes get new ideas for how to present/explain/display something I'm working on.

More importantly though, all geology is related, in a broad sense, and you never know what background info you are going to need to call on to solve a problem.  Today's colloquium talk, or rather the discussion at the end of it, was a really good example of this.

The title of the talk was "Diamond: Deep Carbon from a Shallow Source." The abstract can be found here. It was about isotopes and eclogite and peridotite and diamonds and inclusions. I'll admit, most of the details were beyond me, but I still learned something from it, and I was surprised at how much I could follow (it seems going to talks "unrelated" to my research is paying off, and I'm learning new stuff).

The questions at the end were really a discussion on the still-unknown stages of the formation of diamonds. But someone in the audience had insight that yielded a "wow" from the speaker. It was a petroleum geochemist who specializes in carbon sequestration and biodegradation and other important stuff like that. It might be a bit of a stretch to say that these two researchers, although both geologists and both geochemists, don't have overlapping research (but let's pretend they are completely "unrelated," for the sake of my argument). The petroleum geologist suggested that diamondoids, which are found in petroleum and actually clog up gas wells, might have clues about some of the unknowns.


Most of us were chuckling over the idea of "diamonds" clogging up gas wells, but we could still see the wheels turning as the speaker thought about this new approach to his research and the possibilities it might yield.

My point in all of this, besides the fact that it's kind of cool that there are diamonds that plug gas wells, is that all geology is related and doesn't have to be directly connected to be relevant. And that's pretty cool.

Thinking about not looking up from the path you're on reminds me of something that happened when I was in Bolivia doing field work...
Coming around the bend towards the end of a day in the field, we were so focused on the path in front of us that we almost missed this biotite-bearing outcrop that provided age constraints on the beds we were mapping.  

That's right, we almost missed this outcrop.

Now as it turns out, even if we'd missed the first one, there was still lots of ash around to collect samples from.

But this one is so cool...

In so many ways.

Monday, October 31, 2011

Rugby distraction

I've been distracted for the last two months, partly because I was away for 5.5 weeks, and partly because the Rugby World Cup was on, and I'm a huge (All Blacks) fan.  In fact, my overseas trip was so that I could catch a bit of the rugby in New Zealand, which is like home to me.  I did mix in some geology with my travels: I was on a volcano, I visited some ancient clastics and some modern carbonates. I even did some work on my thesis and a manuscript my supervisor and I are working on. And I watched a lot of rugby, on TV, and in the stadium. I went to five games: three pool matches and two quarterfinals.

When I came back to Canada, I struggled to get over the jet lag, because the rugby was still on, and I was up until 4 or 5am watching the semifinals, and then the bronze final, and then the final. SPOILER: A week later, and I'm still pretty elated about the results.

Now that the RWC is over, I need to get my nose back to the grindstone and finish off my thesis and that manuscript. They're getting there. I'm struggling a bit though, because I'm in rugby withdrawal. So last night I went through some of my photos from Australia, and printed off a few from my outback trip, so that I could look at the really cool geology and be motivated to get some writing done. It also got me thinking about the things I saw that I want to blog about, so now I have a list, and a schedule. Hopefully it will be a nice distraction from writing and figure-making. Anne Jefferson's writing challenge couldn't have come at a better time.

In the meantime, here are a few teaser pictures from my time away (and if anyone knows how I can save them so that the colour doesn't sometimes get changed when they are being viewed, I'd be grateful):
Beside a fumarole on White Island



Valley of the Winds, Kata Tjuta
King's Canyon
Standing beside the Webb Ellis Trophy, two weeks before New Zealand won it

Monday, August 29, 2011

Foreland basins in a nutshell: Part III - Retroarc and peripheral foreland basins

Part I
Part II

The Western Canada Foreland Basin (WCFB) is a retroarc foreland basin. There are two main types of foreland basins, retroarc and peripheral. Both form during collisional tectonics.

A peripheral foreland basin, also known as an Alpine-style foreland basin, forms on the subducting plate (usually during continent-continent collision).

A retroarc foreland basin, also known as an Andean-style foreland basin, forms on the upper plate (usually during continent-oceanic plate collision).

Note: nothing is implied in the scale of the two figures above: there is definitely some vertical exaggeration going on.

I've often wondered if there is a difference in the sediment deposition patterns in the two classes of foreland basins. A reading of Hugh Sinclair's 1997 paper, Tectonostratigraphic model for underfilled peripheral foreland basins: an Alpine perspective, in which he describes the "underfilled trinity," (a favourite term of mine, by the way) felt a lot like reading a description of the Jurassic succession in the WCFB, except that he was describing a peripheral foreland basin. I suspect, therefore, that the sedimentological record alone would not be enough to discriminate between these two types of foreland basin.

In fact, this is what has been found by other authors, such as Dickinson: "Designation of a given foreland basin as either a retroarc basin or a peripheral basin thus depends upon a knowledge of the sequence and timing of tectonic events in the adjacent orogen" (Dickinson, 1974, p21).

Why does this matter? Well, having an "underfilled trinity" in the WCFB means that the foreland basin depositional sequences began appearing sooner than everyone thought, and that fits with what I'm proposing with my research. It also means that although foreland basins contain a record of the adjacent orogeny, we cannot use the basin fill alone to say if it is a retroarc or a peripheral foreland basin. It may seem strange that we wouldn't know this, but recent, and controversial, hypotheses about the evolution of the western margin of North America imply that the western foreland basins are peripheral, not retroarc (and by mentioning this, I'm not saying that I agree with those hypotheses).

In part IV, I'll talk about foreland basin fill: flysche, molasse, backbulges, underfilling...


Dickinson, W. (1974). Plate Tectonics and Sedimentation. In W. Dickinson (Ed.), Tectonics and Sedimentation (pp. 1-27). Society of Economic Paleontologists and Mineralogists.
Sinclair, H. H. D. (1997). Tectonostratigraphic model for underfilled peripheral foreland basins : An Alpine perspective. Geological Society of America Bulletin, 109(3), 324-346. Geological Soc America.

Saturday, August 27, 2011

Childhood memories

A recent twitter discussion that began with me wishing there was a "Tectonics for Toddlers" I could give my nephew got me thinking about one of my favourite toys as a preschooler. It was a Fisher-Price hiking set, and I used to hike around the neighbourhood with it. I always dreamed about going to the coulees behind our yard, but that was forbidden territory to little me (and rightly so--I was only about five years old at the time).

My hiking set is long gone, and a recent Google search turned up an picture of the set in an "old toys" website. But when I go out in the field these days, I still carry some of the same tools, just more grown-up versions of them.

Missing from this picture is the compass that had a mirror on the other side

Friday, August 12, 2011

Accretionary Wedge #37: Sexy Geology

My preference is for big picture geology, especially studying how tectonics influences sedimentation. For this, you need to understand a little bit of everything (or at least be willing to contemplate it). My undergraduate background in geophysics is helpful for understanding geodynamics, and living and studying in Alberta has meant that I've had ample exposure to sedimentary geology in both my degrees. That being said, there are a couple of sedimentary structures that make me swoon. I love a good cross-bedded sandstone. But the one that really gets me is ripples.

I know ripples are pretty common, and I know they aren't great paleocurrent indicators. They are, however, good environmental indicators and for me, seeing a big rippled surface in the field is pretty exciting, especially when it is far away from anywhere it could have formed. What excites me is that they are evidence of tectonics. They've been buried, they've moved,  they've been uplifted and they've been exposed.

There's just something about being up on a ridge, far away from any water and even farther away from a beach, and seeing ripples. It's sexy geology.

Ripples on Dinosaur Ridge, Colorado.
Embiggen to see the scale bar in bottom left.

Ripples in the Puchuni Valley, on the Bolivian Altiplano.
No scale, because this was above me on a narrow path on the edge of a steep hill.

Friday, July 22, 2011

Foreland basins in a nutshell: Part II - Basic definition of a foreland basin

Part 1

Prior to the development of plate tectonic theory, sedimentary basins were discussed in terms of the geosynclinal system, in which basins were described and classified according to their geometry and fill. This was not a simple classification system. For example, in just a two-page Science paper in 1944, Kay described miogeosynclines, eugeosynclines, deltageosynclines and autogeosynclines. He recognized that the original definition, credited to Dana in 1873, had been misused and misinterpreted in the intervening seventy-odd years (Kay, 1951). In its simplest form, Kay defined a geosyncline as "the surface developed at the base of extensive surficial rocks that subsided deeply during their deposition or accumulation," (Kay, 1951, p3).

Kay used the terms eugeosyncline and miogeosyncline to distinguish between geosynclines that either have or lack active volcanism respectively. When discussing orogenies and foreland basins, these are the two historic terms that are most relevant (miogeosynclines are associated with the stable platform and eugeosynclines are associated with volcanic arcs). All of the other named geosynclines are really variations of these two types. For a good overview of geosynclines, and the problems with the theory, I recommend The Story of Geosynclines.

An idealized cross-section through a geosyncline.
Image source:
The mechanisms behind the formation of geosynclines were not always understood, and I think this is a good example of just how unifying plate tectonic theory really is. This was recognized at least as early as 1974, when Dickinson wrote that “the geosynclinal terminology used prior to the advent of plate tectonics is inadequate to describe fully the plate-tectonic settings of sedimentary basins” (p 1).

In fact, it was Dickinson who wrote that despite its emphasis on horizontal movements, plate tectonic theory provided the best mechanism for the large vertical displacements required in order for the thick accumulations of sediment found in some parts of the continent to occur (1974).

Foredeep trough is a term used to describe "an isostatically induced peripheral depression that developed in response to the load imposed on the lithosphere by the ... flow of supracrustal rocks up on to the flank of the craton" (Price, 1973, p 498). Price referred to supracrustal rock flow because he was describing deformation in the southern Canadian Rockies at a Rocky-sized scale of observation.

Even before plate tectonics, the term foreland was being used to describe regions adjacent to orogenic belts (Kay, 1954), but Dickinson (1974) is often credited with first defining foreland basins as such. He redefined eugeosynclines and miogeosynclines to fit within a plate tectonic framework, but, in his own rather eloquent words (p8):
It does not allow for the considerable sophistication of geosynclinal theory in full flower, and results in the unnecessary lumping of things that the full geosynclinal terminology accords different status. Nor does it meet the need to relate various types of sedimentary basins to different kinds of plate interactions, rather than just to the two main kinds of substratum.
Dickinson (1974) designated foreland basins as the retroarc basins on the cratonal or platformal interior of the continent in arc-trench systems, while recognizing that foreland basins can form during continental collisions as well. (This publication, Tectonics and Sedimentation, is also a good read).

The problem I personally have with these definitions is that they tie the formation of a foreland basin specifically to a developing fold-thrust belt. In Western Canada, the Cordilleran Orogeny involved more than just the fold-thrust belt, and I suspect the terrane collisions and subsequent deformation would have caused a flexural response prior to initiation of the thrust faults.

Leckie and Smith (1992) defined a foreland basin as follows: "A succession of sedimentary rocks deposited in a cratonic region adjacent to an active orogenic belt. Sediments are derived mainly from the orogenic belt and thicken toward it." I like this one because it doesn't limit the orogenic belt to the thrust-faults.

Regardless of how it is defined, what a foreland basin is fundamentally the same. It is the basin adjacent and parallel to an active orogeny. The subtle variations in the definitions, do however, impact how the timing of the initiation of the foreland basin is determined; this is one of the major components of my thesis.

The difference between the two types of foreland basins, retroarc and peripheral, will be the subject of part III.

Dickinson, W. (1974), Plate Tectonics and Sedimentation, in Tectonics and Sedimentation, edited by W. Dickinson, pp. 1-27, Society of Economic Paleontologists and Mineralogists.
Kay, M. (1944), Geosynclines in continental development, Science, 99(2580), 461. 
Kay, M. (1954), North American geosynclines, The Geological Society of America, New York.
Leckie, D. A., and D. G. Smith (1992), Regional setting, evolution, and depositional cycles of the Western Canada Foreland Basin, American Association of Petroleum Geologists Memoir, 55, 9–46.
Price, R. (1973), Large-scale gravitational flow of supracrustal rocks, southern Canadian Rockies, Gravity and tectonics, 491–502. 

Tuesday, July 5, 2011

Foreland basins in a nutshell: Part I - Foreland Basin vs. Sedimentary Basin

I study foreland basins. Specifically, I'm looking at the initiation of the western Canada foreland basin and challenging the traditional view of when this initiation took place. In order to do this, I need to use a different definition/model for foreland basins than what has previously been used in western Canada.

Different model, you ask? As I have learned over the last two years, there are different types of foreland basins, and different models for explaining deposition within them. Because I want to have a clear picture of all these different models in my head for my thesis, I'm going to attempt to give an overview of them here.

Today, part I will focus on clearing up a common misconception, at least here in western Canada. The western Canada foreland basin (WCFB) is not the same as the western Canada sedimentary basin (WCSB). The WCSB is the entire sedimentary record in western Canada, beginning with the Belt-Purcell and Windermere deposits in the Proterozoic and continuing through to present times. The WCFB is the sediments deposited during the Cordilleran Orogeny through the Mesozoic and early Paleogene. In the following figure, from the Geological Atlas of Western Canada, you can see the extent of the WCSB. The WCFB is approximately coincident with what is labeled here as the Alberta Basin. However, the foreland basin deposits do actually extend into the Cordillera, like the WCSB does.

Many maps often erroneously depict the western edge of the WCSB and/or the WCFB as being coincident with the eastern edge of Cordilleran deformation (as is the case with the Alberta Basin shown here). Most of the fold-thrust belt contains sedimentary rocks, therefore they are deposited in the WCSB, and in the case of the Mesozoic and Paleogene rocks, the WCFB.

Image source:

In part II, I will look at the most basic definition of what a foreland basin is, and how plate tectonic theory influenced our understanding of foreland basins.

Monday, June 27, 2011

Favourite Geology Word

I've been thinking about the current Accretionary Wedge topic intermittently, because there are a lot of geology words I love, for either phonetic or geological reasons. But I've been preoccupied with my sister's wedding of late, and those words have buried themselves somewhere in the recesses of my mind. Now that I'm back home, I can start thinking about rocks again, and perhaps those words will come back to me.

In the meantime, there is a word that represents a lot of what my master's thesis is about and if used literally, speaks to why I became an earth scientist. Without further adieu, I give you,


Geohistory, or as I more often call it, subsidence analysis, analyzes a sediment column to reveal information about the tectonic conditions it was deposited in. You literally peel back the layers and try to restore the sediments to their depositional conditions. In the case of the master's thesis I am writing write now, I'm looking at subsurface wells in the Western Canada Foreland Basin to show the link between the Cordillera and the foreland basin.

I love this work because it is big picture geology. It ties together the mountains and the basin, and reinforces the fact that you have to understand the regional tectonic framework to study a sedimentary basin.

What does this have to do with why I became a geoscientist? From a very young age, I knew that whatever career I ended up having, I wanted to be a storyteller. I never imagined that I would be reading the rocks to understand and retell the story of the earth, but that's what we all do. In a very literal sense of the term, what we all do is geohistory.

Saturday, June 18, 2011

Word Clouds

I am fascinated with graphic design, and I've been thinking a lot about word clouds lately. I love the look of them. I found a website this morning that makes word clouds, and decided to make one from the abstract for a talk I gave at the CSPG CSEG CWLS Annual Convention in May 2011 (Recovery 2011). Here it is:

Now I just need to figure out how to include something like this in my thesis...

Sunday, June 12, 2011

WOGE #289

Searching for Ron Schott's WOGE #288 felt a bit like being an explorer, following rivers across continents. Even with the last clue helping to narrow down the continent, it still took a while to find the right river. I have a renewed appreciation for the cool patterns left by meandering rivers on their floodplains. I've been casually following WOGE for some months, but I'm sure it is no coincidence that I took the time to really hunt this one down now that I'm supposed to be writing my thesis.

For those of you new to WOGE, the rules can be found here. This is my first time hosting WOGE, so I have no idea if it will be too hard or too easy, but since the last one took more than a few days, I'm not invoking the Schott Rule.

Click on the image to see the full width of the photo (including the North arrow)

Wednesday, June 1, 2011

Mystery traces

For my first post on this blog, I'm going to share some photos of some mysterious traces a friend of mine discovered in August 2010 when we were doing field work in west-central Alberta. I've shown the photos to a few people in the geoscience department at the University of Calgary, but no one knows what it is. My first guess of some sort of cross between a deer and a trilobite seems unlikely.

Maybe there is someone out there who can solve the mystery...

Here's what is known about them:
-Found covering one side of a large boulder in a pile of rocks at the base of some cliffs
-The cliffs are cherty limestone, from the Lower Jurassic Nordegg Member of the Fernie Formation
-The rock is probably also Nordegg, but if it came from high enough up, it could be from the Rock Creek Member. It was wet and muddy and we didn't spend a lot of time figuring out what it was.